Provided by: systemtap-doc_2.3-1ubuntu1.4_all 

NAME
function::stringat - Returns the char at a given position in the string
SYNOPSIS
stringat:long(str:string,pos:long)
ARGUMENTS
str
the string to fetch the character from
pos
the position to get the character from (first character is 0)
DESCRIPTION
This function returns the character at a given position in the string or zero if the string doesn't have
as many characters. Reports an error if pos is out of bounds.
SystemTap Tapset Reference March 2016 FUNCTION::STRINGAT(3stap)